Performance of Iron Phosphate Glass Containing Various Heavy Metal Oxides for Particulate Nuclear Radiation Shielding.

INTRODUCTION: Employees may be exposed to different kinds of ionizing radiation at work. When ionizing radiation interacts with human cells, it can cause damage to the cells and genetic material. Therefore, one of the scientists' primary objectives has always been to create the best radiation-shielding materials. Glass could offer promising shielding material resulting from the high flexibility of composition, simplicity of production, and good thermal stability. MATERIALS AND METHODS: The melt-quenching technique was used to create a glass having the following formula: 50%P2O5+20%Na2O+20%Fe2O3+10%X, where X = As2O3, SrO, BaO, CdO, and Sb2O3 mol %. The impact of the different heavy metal additions on the structure of the glass networks was studied using FTIR spectroscopy. Glass's ability to attenuate neutrons and/or charged particles has been theoretically investigated. The performance of the developed glass as a shield was examined by a comparison against commercial glass (RS 253 G18), ordinary concrete (OC), and water (H2O). RESULTS: For charged particle radiations (Electrons, Protons, and Alpha), the shielding parameters like the mass stopping power, the projected range, and the effective atomic number were evaluated, where S5/Sb glass achieves the best performance. In the case of Neutrons, the results values reveal that S3/Ba glass ( Σ! = 0.105) is the best-modified glass for neutron shielding. CONCLUSION: Among all the investigated glasses, S5/Sb glass composition has a smaller range and provides superior protection against charged particles. In contrast, the S3/Ba glass composition is a superior choice for shielding against neutron radiation.

Recent progress on sonochemical production for the synthesis of efficient photocatalysts and the impact of reactor design.

Sonochemical-assisted synthesis has flourished recently for the design of photocatalysts. The main power used is ultrasound that allows the nanomaterials shape and size modification and control. This review highlights the effect in formation mechanism by ultrasound application and the most common photocatalysts that were prepared via sonochemical techniques. Moreover, the challenge for the suitable reactor design for the synthesis of materials or for their photocatalytic evaluation is discussed since the most prominent reactor systems, batch, and continuous flow, has both advantages and drawbacks. This work summarises the significance of sonochemical synthesis for photocatalytic materials as a green technology that needs to be further investigated for the preparation of new materials and the scale up of developed reactor systems to meet industrial needs.

Different reactor configurations for enhancement of CO2 methanation.

Greenhouse gas emissions are a massive concern for scientists to minimize the effect of global warming in the environment. In this study, packed bed, coated wall, and membrane reactors were investigated using three novel nickel catalysts for the methanation of CO2. CFD modelling methodologies were implemented to develop 2D models. The validity of the model was investigated in a previous study where experimental and simulated results in a packed bed reactor were in a good agreement. It was observed that the coated wall reactor had poorer performance compared to the packed bed, approximately 30% difference between the results, as the residence time of the former was lower. In addition, two membrane configurations were proposed, including a membrane packed bed and membrane coated wall reactor. Additional studies were performed in the coated wall reactor revealing that lower flow rates lead to higher conversion values. As for the bed thickness the optimum layer was found to be 1 mm. In both membrane reactor configurations, the effect of the thickness of M1 membrane, which indicates the membrane for the removal of H2O, didn't show difference while the reduction of the thickness of M2 membrane, which indicates the membrane for the removal of CO2, H2 and H2O, showed better results in terms of conversion.

On the implementation of the circular economy route for E-waste management: A critical review and an analysis for the case of the state of Kuwait.

Electronic waste (e-waste) has become one of the major causes of environmental concerns due to its large volume, high generation rate and toxic environmental burdens. Recent estimates put e-waste generation at about 54 million tonnes per annum with figures reaching approximately 75 million tonnes per annum by 2030. In this manuscript, the state-of-the-art technologies and techniques for segregation, recovery and recycling of e-waste with a special focus on the valorisation aspects of e-plastics and e-metals which are critically reviewed. A history and insight into environmental aspects and regulation/legislations are presented including those that could be adopted in the near future for e-waste management. The prospects of implementing such technologies in the State of Kuwait for the recovery of materials and energy from e-waste where infrastructure is lacking still for waste management are presented through Material Flow Analysis. The information showed that Kuwait has a major problem in waste accumulation. It is estimated that e-waste in Kuwait (with no accumulation or backlog) is generated at a rate of 67,000 tpa, and the imports of broadcasting electronics generate some 19,428 tonnes. After reviewing economic factors of potential recovered plastics, iron and glass from broadcasting devices in Kuwait as e-waste, a total revenue of $399,729 per annum is estimated from their valorisation. This revenue will open the prospect of ventures for other e-waste and fuel recovery options as well as environmental benefits and the move to a circular economy.

Pyro-gas analysis of fixed bed reactor end of life tyres (ELTs) pyrolysis: A comparative study.

Pyrolysis of end of life tyres (ELTs) present a promising alternative to their incineration or classical product recovery using mechanical means. It can produce light hydrocarbons (HCs) and other valuable chemicals as part of the pyro-gas stream it generates. In this work, two grades of tyres namely a fresh (virgin) one and a waste disposed ELTs, were used as a feedstock to analyse their pyro-gas constituents. There wasn't much difference in the maximum conversion rate between both tyre grades where the fresh tyres had an estimated 15.17% conversion and the ELTs was 13.45% conversion (both at 800 °C). The difference herein was attributed to release of free radicals prior to subjecting the samples to pyrolysis due to their history. The analysis of the pyro-gas samples showed a large make of light hydrocarbon (HC) products, namely methane (CH4/C1), ethane (C2H6/C2), ethylene (C2H4), propane (C3H8/C3), propylene (C3H6), n-butane (C4H10), butadiene compounds, carbon mono and dioxide (CO,CO2). Light HCs mimciking natural gas were more abundant in the case of ELTs were C1 was estimated as 14.53% at 500 °C and 16.73% at 800 °C. C2 was also estimated higher than the fresh tyres where a 11.78% at 500 °C was noted and 7.67% at 800 °C. It can be recommended that future integration plans in oil and gas ventures, namely refinery and petrochemical complexes, are to start taking responsible measures towards the environment by substituting part of their operations with sustainable feedstock such as ELTs.

Impact of maternal social vulnerability and timing of prenatal care on outcome of prenatally detected congenital heart disease.

OBJECTIVES: Early prenatal detection of congenital heart disease (CHD) allows mothers to plan for their pregnancy and delivery; however, the effect of certain sociodemographic and fetal factors on prenatal care has not been investigated thoroughly. This study evaluated the impact of maternal and fetal characteristics on the timing of prenatal diagnosis of CHD and fetal and postnatal outcomes. METHODS: This retrospective multicenter cohort study included women with a fetal echocardiographic diagnosis of CHD between 2010 and 2019. Women were grouped into quartiles of social vulnerability (quartiles 1-4; low-high) using the 2014 social vulnerability index (SVI) provided by the Centers for Disease Control and Prevention. A fetal disease severity score (range, 1-7) was calculated based on a combination of CHD severity (mild = 1; moderate = 2; severe, two ventricles = 3; severe, single ventricle = 4 points) and prenatally diagnosed genetic abnormality, non-cardiac abnormality and fetal hydrops (1 point each). Late diagnosis was defined as a fetal echocardiographic diagnosis of CHD after 24 weeks' gestation. Univariate and multivariable regression analyses were used to identify factors associated with late diagnosis, termination of pregnancy (TOP), postnatal death, prenatal-postnatal discordance in CHD diagnosis and severity and, for liveborn infants, to identify which prenatal variables were associated with postnatal death or heart transplant. RESULTS: Among 441 pregnancies included, 94 (21%) had a late diagnosis of CHD. Late diagnosis was more common in the most socially vulnerable quartile, 38% of women in this group having diagnosis > 24 weeks, compared with 14-18% in the other three quartile groups. Late diagnosis was also associated with Catholic or other Christian religion vs non-denominational or other religion and with a lower fetal disease severity score. There were 93 (21%) TOP and 26 (6%) in-utero fetal demises. Factors associated with TOP included early diagnosis and greater fetal disease severity. Compared with the other quartiles, the most socially vulnerable quartile had a higher incidence of in-utero fetal demise and a lower incidence of TOP. Among the 322 liveborn infants, 49 (15%) died or underwent heart transplant during the follow-up period (range, 0-16 months). Factors associated with postnatal death or heart transplant included longer delay between obstetric ultrasound examination at which CHD was first suspected and fetal echocardiogram at which CHD was confirmed and greater fetal disease severity. CONCLUSIONS: High social vulnerability, Catholic or other Christian religion and low fetal disease severity are associated with late prenatal CHD diagnosis. Delays in CHD diagnosis are associated with fewer TOPs and worse postnatal outcome. Therefore, efforts to expedite fetal echocardiography following abnormal obstetric screening, particularly for at-risk women (e.g. those with high SVI), have the potential to impact pregnancy and postnatal outcome among the prenatally diagnosed CHD population. © 2022 International Society of Ultrasound in Obstetrics and Gynecology.

Slow pyrolysis of end of life tyres (ELTs) grades: Effect of temperature on pyro-oil yield and quality.

This study presents the thermo-chemical conversion by means of pyrolysis as a route to valorise end of life tyres (ELTs) in a sustainable manner whilst targeting produced pyrolysis oil (pyro-oil) to replace conventional fossil fuels. The work presented here compares the results of pyro-oil extracted from the pyrolysis of three tyre grades, namely fresh (new) tyres, car and lorry truck ELTs; and investigates the pyro-oil extracted for fuel properties and common fuel hydrocarbon range. A fixed bed reactor system was used to conduct the experimental runs between 500 and 800 °C. The results show that fresh tyres and car ELTs yield some 45% of pyro-oil at an average reactor bed temperature equal to 600 °C which promotes evolution of liquid hydrocarbons via primary route of tyres cracking, hence pyro-oil production to a maximum. Furthermore, and at a similar operating temperature; the diesel range hydrocarbons (C10-C19) were around 66% of the total fuel like chromatograph studied for the pyrolysis oils. The work in this study and based on properties of fuel investigated point towards blending the oil extracted with conventional fuels that could result in lowering dependency on fossil based ones. Further upgrading is also possible whereby desulphurisation could lead to renewable and sustainable fuel source utilising a solid waste feedstock such as ELTs.

Impact of miRNAs expression modulation on the methylation status of breast cancer stem cell-related genes.

PURPOSE: Altered miRNAs play a crucial role in the emergence of the breast cancer stem cell (BCSC) phenotype. The interplay between miRNAs and methylation enzymes has been documented. One of the most aggressive breast cancer cell lines, MDA-MB-231, has expressed much more DNMT3B than DNMT3A. This study aims to evaluate the ability of miR-203 restoration and miR-150 inhibition to regulate DNMT3B and DNMT3A to modify the methylation level of BCSC-associated genes. METHODS: MDA-MB-231 cells were transfected with miR-203 mimic or miR-150 inhibitor or DNMT3B siRNA, and downstream analysis was performed by flow cytometry, real-time PCR and Western blotting. RESULTS: DNMT3A and DNMT3B are regulated both by miR-203a-3p and miR-150-5p. Transfection with miR-203 mimic and miR-150 inhibitor significantly reduced the CD44+CD24- subpopulation and down-regulated the expression of CD44 mRNA by increasing promoter methylation levels. SiRNA knockdown of DNMT3B increased the CD44+CD24- subpopulation and the expression of CD44 and ALDH1A3 by decreasing methylation density. The inhibition of miR-150 down-regulated OCT3/4 and SOX2 expression without affecting methylation levels, while miR-203 restoration and miR-150 inhibition down-regulated NANOG expression by elevating the methylation level. A positive-feedback loop was found between miR-203 and its target DNMT3B, as restoring miR-203 suppressed DNMT3B, while knocking down DNMT3B up-regulated miR-203. The restoration of miR-203 and knockdown of DNMT3B decreased methylation levels and increased the expression of miR-141 and miR-200c. CONCLUSIONS: The study concluded that miR-203 and miR-150 play a role in the regulation of genes involved in BCSC methylation, including other miRNAs, by targeting DNMT3B and DNMT3A.

Three-dimensional numerical modelling of transport, fate and distribution of microplastics in the northwestern Arabian/Persian Gulf.

Marine plastic litter has been a major concern over the past decade particularly in semi-enclosed seas such as the Arabian/Persian Gulf, which are likely to impose a relatively higher threat to ecosystem and human health. In this work, we have focused our efforts on the transport features of marine surface microplastics (MPs) in the Gulf. The assessment utilizes a 3D hydrodynamic model of the northern Gulf which was coupled with a particle tracking model. We have considered five release locations and investigated two dominant wind conditions by applying different numerical scenarios. The results revealed that the northerly winds result in high dispersion and seaward transport of MPs in the open coastal zones, while in semi-enclosed regions they result in high trapping and beaching verified by visual investigation. The study shows that further detailed field investigations are warranted to enable the models to better parameterize the fate and distributions of MPs.

An assessment of microplastics threat to the marine environment: A short review in context of the Arabian/Persian Gulf.

Microplastics are recognised as a (persistent) pollutant and are believed to be ubiquitous in the marine environment. The importance of this issue is evident from the large number of technical publications and research efforts within the past decade. However, the Arabian (Persian) Gulf region has few reported datasets in spite of being an area with excessive plastic use and a hefty generation rate of plastic solid waste. This communication aims at stimulating a discussion on this topic focusing on the available regional and international datasets, along with the environmental conditions that are likely to contribute to the disintegration and transport of the plastic debris rendering it as microplastic. This work also highlights some of the constraints in sampling techniques, identification methods, and the reported units of microplastics. Most studies employ neuston nets of variable dimensions that samples different thicknesses of surface water, which also posses a major constraint in standardising field sample collection. Extrapolation of a trawl to units such as particles.km-2 without considering the fact that neuston nets collect three-dimensional samples, is also another aspect discussed in this communication. This study also intends to initiate a discussion on standardising the practices across the region to enable an intercomparison of the reported data. In addition, it calls for a comprehensive assessment using the standardized methodology for putting a mitigation plan for microplastics as a potential threat detected in environmental sinks.

Evidence of microplastics (MP) in gut content of major consumed marine fish species in the State of Kuwait (of the Arabian/Persian Gulf).

Microplastics (MP), the debris that collectively refers to plastic fragments and particles of <5 mm in size within marine environments, has been the subject of interest within the past decade. Evidence of its occurrence and abundance, has been recorded in this communication after examining gastrointestinal specimens of eight commercially available fish species common to the Arabian (Persian) Gulf acquired locally from the State of Kuwait. The species studied belonged to different trophic levels, and the specimens were subjected to Micro Raman and Micro Fourier Infrared Spectroscopy (FTIR) in Attenuated Reflective Mode (ATR) to determine the presence and type of polymer of the MP. The detected MP set a president for the first time in the examined fish species within the State of Kuwait, which are of immense commercial importance. Various particles were detected, and three MP particles (fragments) were detected within the guts of Acanthopagrus latus, Eleutheronemaa tetradactylum and Lutjanus quinquelineatus. Based on the nature and behaviour of these particular fish types which prefer to stay in muddy waters and sheltered lagoons, it is suspected that common primary sources of MP (i.e. waste fragmentation) have led to passive/active intake (e.g. detritus ingestion) of these particles (fragments) by these species of fish in Kuwait.

Modelling of packed bed and coated wall microreactors for methanol steam reforming for hydrogen production.

A Computational Fluid Dynamics (CFD) study has been conducted to assess the performance of packed bed and coated wall microreactors for the steam reforming of methanol with a CuO/ZnO/Al2O3 based catalyst (BASF F3-01). The results obtained were compared to experimental data from the literature to assess the validity and robustness of the models, and a good validation has been obtained. The performance of the packed bed and coated wall microreactors is similar at a constant reforming temperature. It was found that methanol conversion is enhanced with increasing temperature, residence time, steam to methanol ratio, and catalyst coating thickness. Furthermore, internal and external mass transfer phenomena were investigated using the models, and it was found that there were no internal and external mass transfer resistances for this reactor configuration. Further studies demonstrated that larger catalyst pellet sizes led to the presence of internal mass transfer resistance, which in turn causes lower methanol conversions. The CFD models have exhibited a sound agreement with the experimental data, hence they can be used to predict the steam reforming of methanol in microreactors.

Insights into the evaluation of the abiotic and biotic degradation rate of commercial pro-oxidant filled polyethylene (PE) thin films.

In this study, commercial products formulated from polyethylene (PE) with pro-oxidant additives, were subjected to abiotic and biotic environments. The materials were presumed to be oxo-biodegradable plastics with thicknesses varying between 30 and 70 µm, and calcium carbonate (CaCO3) filler content reaching up to 11 wt%. Accelerated (aging) weathering tests conducted revealed that UV radiation triggered the biodegradation mechanism. Weight loss reached 50% after exposure to weathering which was attributed to triggering the fragmentation of the plastic films. Furthermore, some 83% of weight loss was estimated after 12 months of soil burial. Fluctuation of weight in mid exposure time spans was related to the cross-linking reaction within the polymeric matrix. The mechanical properties investigated along with the thermal stability profile determined for the materials showed that weathering was more severe than soil burial. Thermogravimetry revealed that onset temperature (Tos) was lower than conventional PO products by 25 °C. This could be attributed to the thermal response of the materials due to presence of ion salts and sterates within their composition. The claims by the manufacturing companies which provided the original specimens under an environmentally friendly pretence is disputed due to the fact that none of the products actually showed evidence of major fragmentation or deterioration after exposure to harsh environments. The work also paves the way in standardising assessment methodology for examining biodegradable plastics.

On the Kinetics of Degradation Reaction Determined Post Accelerated Weathering of Polyolefin Plastic Waste Blends.

Polyolefin (PO) polymers constitute the majority of consumer plastic commodities. The reliance on such materials make it near imposable to avoid touching one in any given day. Therefore, the accumulation of plastic solid waste (PSW) in developed and developing societies alike requires immediate attention to manage and valorize this type of waste. In this work, PSW originating from real life sources and virgin linear low-density polyethylene (LLDPE) films were compounded in a mechanical recycling effort. The recycled blends constituted up to 100% (by weight) of the waste material. Accelerated weathering (aging) was conducted on the blends, reaching threshold limit of exposure to study the major changes occurring on the recycled blends. Thermogravimetry and differential scanning calorimetry (DSC) were used to determine their characteristics and applicability for future recycling using thermo-chemical treatment (TCT) methods. Analytical solution methods following the international committee of thermal analysis and calorimetry (ICTAC) were followed in conducting the measurements and kinetic calculations alike. A novel analytical mathematical solution model is also introduced to determine both the pre-exponential factor (Ao) and apparent activation energy (Ea) of the degradation reaction. The model proved to be a more accurate analysis tool, and the work in whole enabled the determination of future plans for using such waste components as a feedstock to thermal units.

Influential parameters on natural weathering under harsh climatic conditions of mechanically recycled plastic film specimens.

In this work, real life reclaimed plastic solid waste (PSW) secured from the municipal sector was mechanically recycled and compounded with virgin linear low density polyethylene (LLDPE). The compounding of the plastic film samples utilised the means of extrusion and blown filming to produce various formulations of the blends containing up to 100% (by weight) of the PSW in the examined specimens. The film samples were compared to market products used in the State of Kuwait where PSW accumulation presents a major obstacle. Natural weathering under arid and harsh climatic conditions was also performed to determine the degradation extent of the film samples. Haze (%), light transmission (%) and the total change in colour (ΔE) were measured as indicators to the degradation profile of the polymeric materials, in addition to tensile pull mechanical properties. Properties were noted to deteriorate as a function of weathering time and waste content. Statistical analysis was also performed on the properties measured and climatic conditions including airborne pollutants levels. The abundance of the secondary airborne pollutant (ozone) was determined to be a significant variable on the studied properties. This can be attributed to induced photo-oxidation the polymeric matrix is subjected to under such climatic conditions which increases oxygen diffusion throughout the polymeric matrix. Future development of the recycled blends studied in this work can be a route for the decrease of associated environmental stressors with virgin plastic resin conversion.

Effect of antimony-oxide on the shielding properties of some sodium-boro-silicate glasses.

Some sodium-silicate-boro-antimonate glasses having the molecular composition [(20) Na2O - (20) SiO2 - (60-x) B2O3 - (x) Sb2O3 (where x takes the values 0, 5 … or 20)] have been prepared by the melt quenching method. The melting and annealing temperatures were 1500 and 650K respectively. The amorphous nature of the prepared samples was confirmed by using X-ray diffraction analysis. Both the experimental and empirical density and molar volume values showed gradual increase with increasing Sb2O3 content. The empirical densities showed higher values than those obtained experimentally, while the empirical molar volume values appeared lower than those obtained experimentally, which confirm the amorphous nature and randomness character of the studied samples. The experimentally obtained shielding parameters were approximately coincident with those obtained theoretically by applying WinXCom program. At low gamma-ray energies (0.356 and 0.662MeV) Sb2O3 has approximately no effect on the total Mass Attenuation Coefficient, while at high energies it acts to increase the total Mass Attenuation Coefficient gradually. The obtained Half Value Layer and Mean Free Path values showed gradual decrease as Sb2O3 was gradually increased. Also, the Total Mass Attenuation Coefficient values obtained between about 0.8 and 3.0MeV gamma-ray energy showed a slight decrease, as gamma-ray photon energy increased. This may be due to the differences between the Attenuation Coefficients of both antimony and boron oxides at various gamma-ray photon energies. However, it can be stated that the addition of Sb2O3 into sodium-boro-silicate glasses increases the gamma-ray Attenuation Coefficient and the best sample is that contains 20 mol% of Sb2O3, which is operating well at 0.356 and 0.662MeV gamma-ray.

A review on thermal and catalytic pyrolysis of plastic solid waste (PSW).

Plastic plays an important role in our daily lives due to its versatility, light weight and low production cost. Plastics became essential in many sectors such as construction, medical, engineering applications, automotive, aerospace, etc. In addition, economic growth and development also increased our demand and dependency on plastics which leads to its accumulation in landfills imposing risk on human health, animals and cause environmental pollution problems such as ground water contamination, sanitary related issues, etc. Hence, a sustainable and an efficient plastic waste treatment is essential to avoid such issues. Pyrolysis is a thermo-chemical plastic waste treatment technique which can solve such pollution problems, as well as, recover valuable energy and products such as oil and gas. Pyrolysis of plastic solid waste (PSW) has gained importance due to having better advantages towards environmental pollution and reduction of carbon footprint of plastic products by minimizing the emissions of carbon monoxide and carbon dioxide compared to combustion and gasification. This paper presents the existing techniques of pyrolysis, the parameters which affect the products yield and selectivity and identify major research gaps in this technology. The influence of different catalysts on the process as well as review and comparative assessment of pyrolysis with other thermal and catalytic plastic treatment methods, is also presented.

Kinetics and product distribution of end of life tyres (ELTs) pyrolysis: a novel approach in polyisoprene and SBR thermal cracking.

Thermo-chemical treatments (mainly pyrolysis) directed towards energy and products recovery provide a very promising alternative to open space disposal or landfilling, reducing in the process hazardous waste and potential contamination to soil and water resources. In this communication, we present results of end of life tyres (ELTs) pyrolysis via isothermal and dynamic thermogravimetry of two ELT grades. The aim of this study is to demonstrate the possibility of utilizing a pre-set temperature (T(c)=500 degrees C) pyrolysis process (conversion time, t(c), of 120 s), to the benefit of intensifying the global product yields recovered. A novel engineering kinetics approach was undertaken to propose a thermal cracking scheme of four primary and two secondary side reactions. Thermal degradation of ELTs was taken from a depolymerization approach of the present polyisoprene polymer in the tyres, resulting in a high regression of 0.959. The products of ELTs pyrolysis were lumped into four categories, namely aromatics, liquids, char and gases. The thermal cracking model evaluation of kinetic rate constants and lumped products showed a regression ranging between 0.90 and 0.94. Dynamic runs were performed to extend the model derived, taking into account heating rate (beta) influence and products prediction and interaction. The results obtained can be used in designing industrial ELTs pyrolysis units.

Recycling and recovery routes of plastic solid waste (PSW): a review.

Plastic solid waste (PSW) presents challenges and opportunities to societies regardless of their sustainability awareness and technological advances. In this paper, recent progress in the recycling and recovery of PSW is reviewed. A special emphasis is paid on waste generated from polyolefinic sources, which makes up a great percentage of our daily single-life cycle plastic products. The four routes of PSW treatment are detailed and discussed covering primary (re-extrusion), secondary (mechanical), tertiary (chemical) and quaternary (energy recovery) schemes and technologies. Primary recycling, which involves the re-introduction of clean scrap of single polymer to the extrusion cycle in order to produce products of the similar material, is commonly applied in the processing line itself but rarely applied among recyclers, as recycling materials rarely possess the required quality. The various waste products, consisting of either end-of-life or production (scrap) waste, are the feedstock of secondary techniques, thereby generally reduced in size to a more desirable shape and form, such as pellets, flakes or powders, depending on the source, shape and usability. Tertiary treatment schemes have contributed greatly to the recycling status of PSW in recent years. Advanced thermo-chemical treatment methods cover a wide range of technologies and produce either fuels or petrochemical feedstock. Nowadays, non-catalytic thermal cracking (thermolysis) is receiving renewed attention, due to the fact of added value on a crude oil barrel and its very valuable yielded products. But a fact remains that advanced thermo-chemical recycling of PSW (namely polyolefins) still lacks the proper design and kinetic background to target certain desired products and/or chemicals. Energy recovery was found to be an attainable solution to PSW in general and municipal solid waste (MSW) in particular. The amount of energy produced in kilns and reactors applied in this route is sufficiently investigated up to the point of operation, but not in terms of integration with either petrochemical or converting plants. Although primary and secondary recycling schemes are well established and widely applied, it is concluded that many of the PSW tertiary and quaternary treatment schemes appear to be robust and worthy of additional investigation.

Establishing an integrated databank for plastic manufacturers and converters in Kuwait.

During the past decade, plastic solid waste (PSW) has increased drastically in the state of Kuwait, amounting to 13% of the waste load. Most ends up in landfills with only a minor percentage being recycled. In this study, a databank was established to include plastic manufacturers and converters in Kuwait. The aim was to assess the amount of plastic waste being generated from a number of sources. Types, quantities, and recycling information were gathered and fed into the databank. Kuwait was divided into five sectors to ease data gathering. A total of 37 companies and agencies related to plastic were integrated into the work, as well as information from a previously established databank for plastic waste bags. It was noted that most converters of plastic use in-house recycling schemes. Grades of polyethylene and polypropylene, as well as aliginic acid, polyacetals, and poly-styrene, are all considered major imports in the Arabian Gulf market, and especially in Kuwait. These grades possess an import value in excess of 20 million US dollars per year. The conclusions from this study could be used in neighboring countries in order to reduce PSW generated from the region.